With 100 percent of precincts reporting, the eight-term lawmaker trailed 44 percent to 50 percent. O'Rourke had been hovering around the key 50 percent mark needed to avoid a runoff all night as results trickled in. The Associated Press called the race a little before 2 a.m.

O’Rourke’s bid was boosted by a Texas-based super PAC, the Campaign for Primary Accountability, which invested heavily in two House contests in the Lone Star State. In the other race where the PAC spent money, the 4th district GOP primary, 16-term Rep. Ralph Hall won easily.

Reyes is a former chairman of the House Permanent Select Committee on Intelligence and a former chairman of the Congressional Hispanic Caucus. He currently serves as a senior Democrat on the Armed Services Committee.

Reyes was not surprised. Acknowledging the tough primary, his campaign spent more than $460,000 and both sought and secured the endorsements of Presidents Barack Obama and Bill Clinton, who has had a decent record of backing winners in Democratic House primaries this cycle. Clinton campaigned for Reyes at a rally in El Paso last month.

O'Rourke spent at least $280,000 on his campaign this year. He should be considered a shoo-in to win the general election in the heavily Democratic 16th district.

Reyes is the sixth House Member to be defeated in a primary this cycle, although three of those Members lost to another Member in a redistricting-forced contest. To see which other Members have lost check out our Casualty List.